1. Field
Embodiments of the present invention generally relate to implantable medical devices having porous, honey-comb like structures, and more specifically methods of constructing such devices with integrated porous technology using an Electron Beam Melting (EBM) additive manufacturing process.
2. Description of Related Art
In the implanted medical device field it is well established that coating a solid prosthesis with a porous layer promotes the ingrowth of bone into the surface of the implant. Bone ingrowth results in better adhesion between the implanted device and the adjoining bone for better short- and long-term fixation of the implant. Over the years, many different methods of manufacturing implant devices with porous coatings have been researched and developed. The research has focused, not only on methods of attaching coatings to a base or core substrate material, but also on the material and morphology of the coatings themselves. Methods that involve one or more intermediate phases between the substrate material and the coating, or several layers of the same coating have also been developed.
Many of these methods require multiple processing steps to achieve the final porous coated metallic implant. Some of these steps could include, cleaning, acid etching, plasma spraying, diffusion bonding, and sintering. Not only are most of the developed methods time consuming and expensive, but several of the methods have been shown to have negative effects on the mechanical properties of the parent substrate material. Many methods, such as diffusion bonding, thermal deposition, and sintering involve high temperature heat treatments that may decrease the performance characteristics of the initial solid prosthetic component to which the coating is applied.
As a result many of these methods aim to minimize the impact of heat treatment on the properties of the parent material, which could lead to poor adhesion between the parent material and the porous coating. A weak coating-substrate interface can lead to third body wear in joint applications, where the porous material detaches from the substrate and migrates to the joint wear surfaces creating premature wear and failure of the devices.